If you go in for a $49.99 special ask specifically what they are going to do and how they are going to do it. Personally I want the pan dropped and cleaned out along with the magnet. A fluid exchange by a machine is the easy way of changing the fluid and does not accomplish that. In fact, depending on the pressure involved, it might just stir up any debris in the pan. If the word "reverse flush" is mentioned, run like a pair of cheap pantyhose.

Not sure what to say about the MPG display.

05-10-13, 12:48 PM

c_d

Re: sporadic SES light and exotic codes

I have done some routine maintenance yesterday and while the car was jacked up anyway, I checked the parts of my friends car. Just as with my old Caddy, the problems never stop:

The rear shocks are leaking massively. After telling my friend a rough guesstimate about the DTS shocks he almost fainted. We have a pick&pull with a huge Deville stock about 15m away, would it be possible, advisable or whatever to just bridge the remaining years of the car. It has 135k miles already and spending another $2k on just the rear shocks is steep.

I located and fixed another vacuum leak. However, the car is shaking a lot just after start up with a cold engine. It goes away after two minutes. There is also a noticeable loss of power during this time. The engine is purring afterwards and runs strong.

Does the Deville DTS has some kind of rpm delimiter? When in N, the needle goes to ~4200 and jumps back to 3500. This is also the point in which a slight hesitation appears when in D and just push the pedal to the metal.

Next thing on the list is the transmission fluid change.

05-10-13, 02:08 PM

Submariner409

Re: P0174 on a 04 Deville

The engine has an rpm limiter at about 4,000 in P or N - to keep you (us) from trying to over-rev an unloaded engine.

Engine miss for 30 - 45 seconds after cold start is NOT GOOD. That's one of the telltale signs of failing head gaskets: The engine cools, a tad of coolant leaks into a cylinder(s). You start the car, the coolant shorts the plug electrodes to ground for some number of revolutions - the coolant blows out the exhaust port(s) and the engine smooths out.

Used rear height control shocks are a crap shoot - but cheaper than the new article. Your (his ?) call.

05-10-13, 02:24 PM

c_d

Re: P0174 on a 04 Deville

Quote:

Originally Posted by Submariner409

The engine has an rpm limiter at about 4,000 in P or N - to keep you (us) from trying to over-rev an unloaded engine.

Engine miss for 30 - 45 seconds after cold start is NOT GOOD. That's one of the telltale signs of failing head gaskets: The engine cools, a tad of coolant leaks into a cylinder(s). You start the car, the coolant shorts the plug electrodes to ground for some number of revolutions - the coolant blows out the exhaust port(s) and the engine smooths out.

Used rear height control shocks are a crap shoot - but cheaper than the new article. Your (his ?) call.

Argh, Sub - I thought this HG business was resolved in the 2004 model year :-( That would be bad news to carry.

05-10-13, 02:30 PM

Submariner409

Re: sporadic SES light and exotic codes

Quote:

Originally Posted by c_d

There is only one but I should have mentioned that: 2004 Deville DTS.

Just so we all know ............

05-10-13, 03:00 PM

c_d

Re: sporadic SES light and exotic codes

Quote:

Originally Posted by Submariner409

Just so we all know ............

Dang, I put that thing back in the car list. However, I usually don't have access to the car. Anyway, would this initial misfire show up at a ODB reader with monitoring? You have me highly concerned here.

05-10-13, 04:20 PM

Ranger

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

If it's an '04, I wouldn't worry much about the HG. While anything is possible, it's not too likely.

Junkyard shocks are a crap shoot, but if your only intention is to "bridge the remaining years", it can't hurt to try.

05-10-13, 11:55 PM

c_d

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Quote:

Originally Posted by Ranger

If it's an '04, I wouldn't worry much about the HG. While anything is possible, it's not too likely.

Junkyard shocks are a crap shoot, but if your only intention is to "bridge the remaining years", it can't hurt to try.

Phew I hope not. The owner is a big Cadillac fan but with even less knowledge about working on a car than me. After I fixed the one vacuum leak (plenum still pending) and changed the air filter, oil filter, and oil yesterday, I took it for a spin. On the positive side, the MPG went up to 17. Anyway, I also snapped a video of a cold start. I was hoping for a better sound quality but I still have hopes one of your guys may have magic ears and hear something: http://youtu.be/N9OBVyOaRME

05-11-13, 11:10 AM

Ranger

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Not sure what I was listening for, but I didn't hear a thing. I DID notice that the temp gauge seemed to rise rather quickly.

05-11-13, 11:45 AM

c_d

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Quote:

Originally Posted by Ranger

Not sure what I was listening for, but I didn't hear a thing. I DID notice that the temp gauge seemed to rise rather quickly.

Thanks for the reply ranger - it is a mystery for me, the engine sounds a little rough, my OBD reader is not uncomplaining, no codes are accessible by the in-dash but the car is shaking (the camera was fixed, all shaking comes from the car). The temp gauge is indeed quick, I always accounted hat to the ambient temperature >85F and a very sunny parking spot. He had a mechanic do some repairs in January because of leaking coolant and something in the lines of a coolant crossover was replaced (as well as the master cylinder).

05-11-13, 06:16 PM

Submariner409

Re: P0174 on a 04 Deville

That C tick is 90 degrees or so, ambient 85 - 1 minute 30 seconds - I see the same rise by the time I get 400 yards up the road .............. but not when ambient temp is 45 degrees outside .....................

FWIW, On a nice, sunny day in June here, ambient 93 degrees, I have seen the temp "gauge" needle start at one needle width above the C tick before starting the engine from "cold".

05-12-13, 12:06 AM

Ranger

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Hmm, perhaps I spoke too soon then. I never really paid that close of attention to just how fast that gauge rises.

05-12-13, 02:25 AM

Manic Mechanic

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

c-d, reading through this I noted the car was driven to Galveston. Where is SAT/BER? Or where is the car's home? Galveston is close enough to my part of the country to ask just in case the next point is not understood. My only guess is San Antonio Texas for the first and no guess for BER. In any case if you are unable to solve this I can in a hour or less.

As for the car, you have a problem that effects the air to fuel ratio calculated by the fuel injection computer (PCM). It is most apparent at cold starts because the fuel injection is still in "Open Loop" whereas the Oxygen Sensors are not yet hot enough to provide Air/Fuel ratio feed-back to the PCM for correction. This is why you are seeing repeat lean codes and have rough running on a cold start that clears up as soon as the O2 sensors start reporting the problem to the PCM. It could be mechanical such as a vacuum leak anywhere in the intake system. It could also be electrical, as the Mass Air-flow Sensor (MAF) and the Manifold Absolute Pressure (MAP) sensor may be damaged or dirty causing it to report an incorrect signal to the PCM. If one of those two signals is substantially askew it would explain all the problems also. The reduced mileage and lack of power goes with these possibility's. You have no symptoms of a blown head gasket at this time.

First test is this. With the engine cold again, before you start it, unplug the MAF sensor. This it the sensor on top of the air cleaner with the accordion tube going to the throttle body. Then start the engine and note if the engine runs worse or better. The check engine light will be on as long as it is being tested this way and will stay on with codes for the MAF signal low until you reset it. But in the meantime if it runs worse replace the MAP sensor on top of the coolant bridge. Second test, if it runs fine or better start driving it like that and note if it runs better under load where you say it's laying down now (pedal to metal in Drive). If it seems better try cleaning the MAF sensor as described in countless prior threads. If after cleaning and reconnecting the plug to the MAF it reverts to poor operation have the intake system smoke checked by a pro with the correct machine for doing this. If no vacuum leaks are found the MAF will have to be replaced as it is likely the problem. Sometimes the sensors loose their calibration but not far enough to set a code. You have one of these problems at least.

As to the problem with Uxxxx codes, these are communication codes. These along with resetting monitors at start-up point to a bad ground connection. Most often it's the big cable ground connecting the alternator housing to the RH front frame rail. Grab ahold of it and give it a tug. If it breaks or stretches that's the problem. If not clean and retighten the bolt's on each end. Check the three ground leads on the front of the transmission. They are down on the LH front of the case below the air cleaner and water pump next to the ABS pump and valve block. They each have a bolt clamping them onto the transmission. Clean and tighten all three connections. In fact it would be wise to sort the bad ground problem out before starting on the Air/Fuel ratio issue as the bad ground could easily be causing the sensors to be out of calibration.

Salvage parts from the local pick & pull yard are acceptable in all the instances above provided they look in better shape than the originals. Be sure to clean any sensors with electronic cleaner before use.

If the fluid monitor is reporting the transmission fluid is 50% depleted multiply the current mileage by 2 and you'll have the approximate point that the fluid has to be changed. Before then it's just a preventative measure.

Vernon

05-12-13, 12:04 PM

Ranger

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Quote:

Originally Posted by Manic Mechanic

c-d, reading through this I noted the car was driven to Galveston. Where is SAT/BER?
Vernon

SAT is San Antonio. My guess is that Ber is short for Boerne (just north of SAT) because BER is technically Berlin Germany.

05-12-13, 12:05 PM

Ranger

Re: Sporadic SES light and exotic codes - friend's 2004 DTS

Quote:

Originally Posted by Manic Mechanic

c-d, reading through this I noted the car was driven to Galveston. Where is SAT/BER?
Vernon

SAT is San Antonio. My guess is that Ber is short for Boerne (just north of SAT). BER is technically Berlin Germany.